Packet based networks are formed of a plurality of layer-2 networks connected by routers. The layer-2 networks may include local area networks (LANs) metropolitan area networks (MANs), wide area networks (WANs) and simple links. For the simplicity of the following description the term LAN is used to represent all layer-2 networks, unless specifically stated otherwise. The routers receive packets from one LAN to which they are connected and pass the packets through the same or a different LAN in an operation referred to as routing. In the routing act, the router determines the LAN through which the packets are forwarded and selects a layer-2 MAC address with which the packet is forwarded on the determined LAN. The routing operation requires suitable configuration of the router in accordance with the computers and networks which the router services. Layer-3 switches are switches which perform the tasks of routers, in addition to layer-2 bridging tasks.
Some routers and layer-3 switches perform other tasks in addition to the routing. Some of these tasks, referred to cumulatively as policy enforcement, include, for example, access control, quality of service (QoS) determination, sniffing (i.e., passing certain packets to an additional station) and packet counting.
Router acceleration switches perform some of the routing which should be performed by one or more adjacent routers (i.e., routers included in the same layer-2 network). The routing is performed by the acceleration switch based on information sent within the LAN, e.g., to/from the adjacent router, and the acceleration switch does not require configuration in order to perform the routing. The acceleration switch intercepts packets, which it knows how to route, on their way to the adjacent router and routes them directly to their destination or to a next hop on their way to their destination. Packets which the acceleration switch does not know how to route are bridged in layer-2 to the adjacent router. Thus, the packets routed by the acceleration switch do not reach the adjacent router, the load on the adjacent router is reduced and the throughput of the network is increased. These advantages are referred to as router acceleration and the adjacent router is referred to as the accelerated router.
Generally, in order to operate in a policy enforcement environment the policy rules must be configured into the acceleration switch. This, however, reduces the effect of an advantage of acceleration switches, which is that acceleration switches do not require configuration.